The present invention generally relates to a motor vehicle and more particularly, to a suspension apparatus for rear wheels of the motor vehicle.
Conventionally, in rear suspension apparatuses for motor vehicles, it has been so arranged that a pair of trailing arms are provided at opposite sides of a body of the motor vehicle so as to extend in a longitudinal direction of the body such that a forward end of each of the trailing arms is pivotally supported by the body and a backward end of each of the trailing arms secures the rear wheels rotatably. However, the prior art rear suspension apparatuses have such an inconvenience that the trailing arms have a low transverse rigidity. Furthermore, there have been proposed an axle type suspension apparatus in which backward ends of opposite trailing arms are coupled with each other by a beam so as to enhance its transverse rigidity and an arrangement in which central portions of opposite trailing arms are coupled with each other by a torsion beam such that variations of camber with respect to the body are maintained at the same level as those of independent suspension apparatuses of semi-trailing arm type so as to obtain advantages of both the axle type and the semi-trailing arm type as disclosed, for example, in U.S. Pat. No. 4,165,099. However, in the latter arrangement, adequate consideration is not given to influences upon the torsion beam and upon coupling portions between the torsion beam and the trailing arms exerted at the time of application of vertical loads to the rear wheels. Namely, in the latter arrangement, when a vertical load is applied to the rear wheels, the torsion beam is subjected to bending deformation such that compressive stress and tensile stress are, respectively, applied to an upper face and a lower face thereof, so that the lower face is fatigued more than the upper face and thus, such undesirable phenomena may readily take place that the torsion beam is ruptured rapidly and coupling portions between the lower face of torsion beam and the trailing arms are ruptured due to a tensile force applied to the coupling portions.